Role of Distant Al Atoms in Alkaline Earth Zeolites for Stabilization of Hydroxyl Groups

• Published in: Journal of physical chemistry. C Vol. 116; no. 3; pp. 2399 - 2410
• Main Authors: Larin, Alexander V, Rybakov, Andrey A, Zhidomirov, Georgy M
• Format: Journal Article
• Language: English
• Published: American Chemical Society 26-01-2012
• Subjects: C: Surfaces, Interfaces, Catalysis
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp205028c

The traditional point of view about water cleavage at divalent cations in alkaline earth (AE) mordenite (MOR) and faujasite (FAU) zeolites was not supported by energy analysis at both the isolated cluster level and the computations with periodic conditions if the cation is located in the vicinity of both Al atoms. A new hypothesis about the kinetic (and not thermodynamic) stabilization of hydroxyl groups near one noncompensated distant Al atom is verified theoretically to explain the acidic nature of the AE cationic MOR and FAU forms. This model allows the development of qualitative interpretation of the temperature variations in the IR spectra upon hydration, dehydration, and rehydration.